Ac operated magnet

ABSTRACT

A magnet with laminated core and armature arranged for operation with AC current. A plastic casing surrounds the laminated iron in the core and armature members and subdivides the lamination into two identical sections. The intermediate plastic layer which subdivides the lamination serves as an impact surface between the armature and the core member of the magnet. The laminations are reinforced and held together through plastic filled notches, as well as stress takeup rods.

United States Patent [72] Inventors Gerhard Widl Ditzingen; KurtGroetzner, Stuttgart-rot; Adolf Knodler, Fellbach, Germany [21 Appl. No.797,583

[22] Filed Feb. 7, 1969 [45] Patented May 4, 1971 [73] Assignee RobertBosch G.m.b.H.

Stuttgart, Germany [32] Priority Feb. 28, 1968 [3 3] Germany [54] ACOPERATED MAGNET 7 Claims, 9 Drawing Figs. [52] US. Cl 335/248, 335/277,335/279, 335/281 [51] Int. Cl HOlf 7/12 [50] Field of Search 335/243,

[56] References Cited UNITED STATES PATENTS 2,370,752 3/1945 Ray335/281X 2,715,199 8/1955 Bogue et al. 335/251X 3,042,842 7/1962 COX335/260X Primary ExaminerG. Harris Att0rneyMichael S. Striker ABSTRACT:A magnet with laminated core and armature arranged for operation with ACcurrent. A plastic casing surrounds the laminated iron in the core andarmature members and subdivides the lamination into two identicalsections. The intermediate plastic layer which subdivides the laminationserves as an impact surface between the armature and the core member ofthe magnet. The laminations are reinforced and held together throughplastic filled notches, as well as stress takeup rods.

PATENTEUHAY 4m: 3,577.10?

sum 10F 3 Wren/raps f/re/r Arrow/5y v The present invention resides inan AC electromagnet or solenoid applicable particularly for theactuation of hydraulic valves. The AC electromagnet or solenoid has anarmature and a core constructed of laminated ferromagnetic material.

Conventional AC electromagnets of the preceding species have solderedlaminations or laminated sections. When applied to the operation ofhydraulic valves, in which considerable power requirements are involved,the soldered magnetic construction of such magnets are subjected tosevere shear forces. As a-result of this condition, such conventionalmagnets have a relatively limited lifespan.

Accordingly, it is an object of the present invention to provide an ACoperated electromagnet or solenoid with increased lifespan or operatinglife. It is also an object of the present invention to produce such anelectromagnet of the aforementioned properties, in an economical manner.

The preceding objects of the present invention are achieved bysurrounding at least partially the armature and/or core of I the magnetwith plastic material.

A particular advantageous embodiment of the present invention resultswhen the laminated section or unit is subdivided into as least twoadjacent and identical laminated sections. A plastic intermediate layeror layer of synthetic material separates the two identical sections.This construction diminishes the required pressure to be applied forholding together the laminations of the armature and/or the core.

' The plastic intermediate layer of the annature and/or core is designedso that the surface of impact between the armature and the core hasdamping characteristics. In the design of the present invention, thelaminated elements are furthermore particularly well held togetherthrough the provision of at least one bore running vertical to theplanes of the laminated elements of the armature and/or core. An elasticmetallic member, preferably of rolled spring steel, and in the form of astress resisting rod is inserted into the bore and covered ormolded-over with plastic material.

SUMMARY OF THE INVENTION An AC operated magnet in whichthe core memberand the armature are both of laminated iron. A plasticcasing or coveringsurrounds at least partially either or both the core and the armaturewhich is movable relative to the core. A plastic intermediate layersubdivides the armature and/or the core into at least two identicalsections, and may be approximately twice as thick as the jacket orcasing surrounding the outer rim of the armature or core. Elasticdeformable plastic elements are inserted into the impact surfaces of thearmature and/or the core to decrease the impact effects when thearmature is actuated.

The novel features which are considered as characteristic for theinvention are-set-forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an isometric view of anactuating magnet or solenoid which is subdivided into laminated sectionsthrough an intermediate plastic layer, in accordance with the presentin- ,vention;

FIG. 6 is a sectional view of the annature taken along lines Vl-Vl inFIG. 4;

FIG. 7 is a sectional view of an embodiment of the arms ture, inaccordance with the present invention, and shows the design in whichonly one stress takeup or supporting rod abutting an injection moldedactuating rod;

FIG. 7a is a sectional view of another embodiment of the armature; and

FIG. 8 is an isometric view of a core of a magnet, and shows anembodiment for admitting two through-bolts into openings provided in thecore.

DESCRIPTION OF THE PREFERRED EMBODIMENTS molded portions 11. Thesecuring of the laminated members to the baseplate can also beaccomplished with screws or bolts. A core member 12 consists oflaminated sheet metal embedded in plastic material. Bores 13 on bothsides of the core run along the legs of the core, as shown in FIG. 8.These bores are symmetrically located with respect to the central axisof the magnet. The bores lie outside of the striking or actuating regionof the armature 14. The movable armature 14 functions in conjunctionwith the core 12. The bores 13 are directed along the axial direction ofthe magnet, and lie within an intermediate plastic portion 15 whichsubdivides the laminated structure 16 of the core 12 into twoneighboring sections and 16 b. The two laminated sections 16a and 16bare of identical design and construction. The laminated construction ofthe armature I4 is separated into two identical laminated sections 18aand 18b, through a plastic intermediate layer or portion 17.

The intermediate portions 15 and 17 of the armature and the core'have athickness substantially equal to either one of the two respectivelaminated sections in the armature and the core. Thus, the intermediateportion 15, for example, is as thick as either the section 16a and 16b,while the intermediate plastic portion 17 is as thick as either thesection I 8a or 18b. These intermediate plastic portions 15 and [7connect with the neighboring surfaces of the armature and the core withtheir associated laminated sections, similar to the bordering portions19 and 20, also made of plastic material. The intermediate portions 15and 17, in this manner, form striking or abutting surfaces which lie inthe same plane as the pole surfaces of the magnetic system.

An actuating rod 21 is inserted in the plastic intermediate layers 17 ofthe armature 14. This actuating rod projects with a portion 22 out ofthe armature and in the direction for attracting the armature by thecore. This portion 22 of the actuating rod 21 extends into an opening 23provided within the intermediate plastic layer 15 of the core 12. It isthe purpose of this extending portion 22 to actuate a hydraulic valve,not shown. With its opposite end or portion 24, the actuating rod 21passes through the housing of the magnetic system, not shown, so thatthe valve may also be manually actuated in the event that this becomesnecessary. This construction is shown in FIGS. 1 and 2,

FIG. 3 shows an armature with an actuating rod 21 which has only aprojecting end portion 22 for extending into the core and the-baseplate.A rubber ring 25 lies around the actuating rod 21 in the region wherethe rod exits from the armature. This rubber ring prevents fracture ofthe plastic material as a result of small deflections of the rod orinclinations of the rod in this particular region.

FIG. 4 illustrates an embodiment of an actuating magnet or solenoid inwhich the laminated section 16 of the core 12 is not subdivided orseparated through a plastic intermediate layer. For the purpose ofproviding more complete cooling of the laminations, recesses 26 areprovided about the outer side surface s. An actuating rod 27 is heldwithin the baseplate l supporting rods 30 are provided in bores 31perpendicular to the layer planes of the laminations. These shearsupporting 'rods 30.are inserted into bores and are covered with plasticmaterial. When the armature strikes the core, the resulting shearstresses or shear forces that arise from this action, are largely takenup by these shear supporting rods 30. The locations and designs of theserods are shown in H65. 5 and 6.

FIG. 7 shows an annature design in which recesses 32 and 33 are providedin the striking portion or impact portion of the armature which strikesor contacts the core. These recesses 32 and 33 are filled with plasticmaterial for the purpose of in creasing the elastic properties of thiscontact portion of the armature, and to prevent damage to the relativelythin rim 19, when the armature comes into contact with the core. Thus,the plastic inserts 32 and 33 serve to protect the surface of thearmature when striking the core, after becoming actuated.

The armature 14, shown in FIG. 7a, is exactly like the armature shown inFIG. 7, except that the recesses 33, filled with a synthetic plasticmaterial, have a shape that is different from the recesses 32.

.The plastic material used in the design of the aforementionedembodiments are formed through injection molding techniques, and are ofnylon reinforced with glass fibers, known in the art as Nylafil G l0/40.

When the armature l4 becomes actuated and is attracted to the core, inthis AC magnet arrangement, the armature becomes rapidly accelerated asa result of the varying inductance of the magnetic system, and thenstrikes with high velocity upon the core 12.

It has been found in practice that magnets in which the laminatedelements are held in place through elastic deformable plastic covering,have more resistance to shear forces than magnets with soldered ironcores. This applies even to the condition when the plastic surroundingthe laminated sections and elements are of relatively small quantity ormass. In plastic covered iron cores, furthermore, the cohesion of thelaminations is further improved, since the plastic penetrates throughbores 31 in the laminations or laminated sections. The lifespan of theAC- magnets, in accordance with the present invention, is alsoconsiderably increased through the presence of the elastic and flexibleshear supporting rods or stress rods in-- .serted into the bores 31 andcovered or molded over with plastic. These stress takeup rods take upthe shear forces which arise in the operation of the magnet. Throughsubdivid ing the laminated unit into two or more thin laminatedsections, furthermore, the required pressure for packaging the laminatedsections becomes diminished. The plastic intermediate layer as well asthe plastic surrounding covering, in addition, provides damping effectsof the armature impact in striking the core.

It will be understood that each of the elements described above, or twoor more together, may also find a useful applicat'ion in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in ACmagnets, it is not intended to be limited to the details shown, sincevarious modifications and structural changes may be made withoutdeparting in any way from the spirit of the present writing.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

lclaim:

1. An AC operated magnet comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; a plastic casing covering at leastpartially one of said members; and plastic means filled in recesses ofsaid armature member and exposed to the impact surface between saidarmature and said core member, said impact surface being a surface alongwhich said armature member strikes said core member when said magnet isactuated.

2. An AC operated magnet comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; a plastic casing means covering at leastpartially one of said members; a plastic intermediate layer forsubdividing the laminated iron in at least one of said members into atleast two identical sections; and actuating rod means projecting fromsaid intermediate layer means of said armature member and passingthrough an opening in said core member, said opening being through aplastic intermediate layer in said core member subdividing saidlaminated iron into at least two sections in said core member.

3. An AC operated magnet comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; a plastic casing covering at leastpartially one of said members; at least one stress takeup member in anopening perpendicular to the planar surfaces of said laminated iron ofat least one of said members, said stress takeup member being of elasticmetallic substance.

4. An AC operated magnet comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and moveablerelative to said core member; a plastic casing covering at leastpartially one of said members; at least one stress takeup member in anopening perpendicular to the planar surfaces ofsaid laminated iron of atleast one of said members; and plastic means covering said stress takeupmeans.

5. The AC operated magnet as defined in claim 3 wherein said elasticmetallic substance comprises spring steel.

'6. An AC operated magnet, comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; plastic casing means covering said membersfor holding the laminations of said laminated iron in assembledposition; elastic deformable plastic layers on said armature member andsaid core member between the surfaces of impact of said armature memberand of said core member; and plastic means in at least one recessperpendicular to the planar surfaces of said laminated iron of at leastone of said members.

7. An AC operated magnet, comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; plastic casing means covering said membersfor holding the laminations of said laminated iron in assembledposition; elastic deformable plastic layers on said armature member andsaid core member between the surfaces of impact of said armature memberand of said core member; and at least one stress takeup member in anopening perpendicular to the planar surfaces of said laminated iron of aleast one of said members.

1. An AC operated magnet comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; a plastic casing covering at leastpartially one of said members; and plastic means filled in recesses ofsaid armature member and exposed to the impact surface between saidarmature and said core member, said impact surface being a surface alongwhich said armature member strikes said core member when said magnet isactuated.
 2. An AC operated magnet comprising, in combination, a coremember of laminated iron; an armature member of laminated iron andmovable relative to said core member; a plastic casing means covering atleast partially one of said members; a plastic intermediate layer forsubdividing the laminated iron in at least one of said members into atleast two identical sections; and actuating rod means projecting fromsaid intermediate layer means of said armature member and passingthrough an opening in said core member, said opening being through aplastic intermediate layer in said core member subdividing saidlaminated iron into at least two sections in said core member.
 3. An ACoperated magnet comprising, in combination, a core member of laminatediron; an armature member of laminated iron and movable relative to saidcore member; a plastic casing covering at least partially one of saidmembers; at least one stress takeup member in an opening perpendicularto the planar surfaces of said laminated iron of at least one of saidmembers, said stress takeup member being of elastic metallic substance.4. An AC operated magnet comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and moveablerelative to said core member; a plastic casing covering at leastpartially one of said members; at least one stress takeup member in anopening perpendicular to the planar surfaces of said laminated iron ofat least one of said members; and plastic means covering said stresstakeup means.
 5. The AC operated magnet as defined in claim 3 whereinsaid elastic metallic substance comprises spring steel.
 6. An ACoperated magnet, comprising, in combination, a core member of laminatediron; an armature member of laminated iron and movable relative to saidcore member; plastic casing means covering said members for holding thelaminations of said laminated iron in assembled position; elasticdeformable plastic layers on said armature member and said core memberbetween the surfaces of impact of said armature member and of said coremember; and plastic means in at least one recess perpendicular to theplanar surfaces of said laminated iron Of at least one of said members.7. An AC operated magnet, comprising, in combination, a core member oflaminated iron; an armature member of laminated iron and movablerelative to said core member; plastic casing means covering said membersfor holding the laminations of said laminated iron in assembledposition; elastic deformable plastic layers on said armature member andsaid core member between the surfaces of impact of said armature memberand of said core member; and at least one stress takeup member in anopening perpendicular to the planar surfaces of said laminated iron of aleast one of said members.